<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>fieldset legend标签</title>
    <style type="text/css">
        .div span{
            position:absolute;
            left:13.5%;
        }
    </style>


</head>
<body>
<form action="" method="get">
    <fieldset class="div">
        <legend class="div">健康信息</legend>
        <label>身高：<input type="text" name="height" id="height"><span>cm</span></label>
        <label>体重：<input type="text" name="weight" id="weight"></label>
    </fieldset>
</form>
</body>
</html>